Molecular Identification of a Densovirus in Healthy and Diseased Zophobas morio (Coleoptera, Tenebrionidae).

Zophobas morio is a tropical darkling beetle which is widely exploited for commercial large-scale insect growing. Outbreaks of a disease may occur causing total devastation of cultures. In the present paper, samples of diseased Z. morio were obtained and used for establishment of a laboratory model as they were found infective to the larvae of the same insect species from another source. It took about 1 month to develop symptoms of acute disease in mid-age larvae and about twice as much when younger larvae were used for infection. Affected larvae perished quickly, and within several days up to 90-100% of the colony could perish. Both in healthy and diseased larvae a virus was detected using PCR with degenerate primers specific for a gene coding for a non-structural protein (ORF3). The sequenced gene fragment (Genbank accession #MN732869) confirmed allocation of the virus to Densoviridae, with maximal similarity of 97.2% to Blatella germanica densovirus-like virus (#JQ320376) and 66.2% to B. germanica densovirus (#AY189948). Genomic DNA samples of Z. morio larvae from an independent colony devoid of symptoms of a disease were also positive for this virus with a slightly different (99.7% sequence similarity to the former sequence of the Z. morio densovirus) genotype (#MN732870).